Process and apparatus for separation of ores by flotation.



A. W. THOMPSON & D. COLE. PROCESS AND APPARATUS FOR SEPARATION OF ORES BY FLOTATlON.

APPLICATION FILED JAN. 13. I916.

Patented Apr. 18, 1916.

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link} IrivenToPs. NberT W. Thompson David Co\e V AHya.

UNITED STATES PATENT onnic.

ALBERT W. THOMPSON, F FITCHBURG, MASSACHUSETTS, AND DAVID COLE, OF

EL PASO, TEXAS; SAID THOMPSON ASSIGNOR TO THE G. M. PARKS COMPANY, OF

FITCHBURG, MASSACHUSETTS. A CORPORATION OF MASSACHUSETTS.

PROCESS AND APPARATUS FOR SEPARATION OF OR-ES BY ELOTATION.

Application filed January 13, 1916.

To all whom it may concern:

Be it known that we, ALBERT V. THOMP- soN, a citizen of the United States. and resident of Fitchburg,'county of \Yorcester, State of Massachusetts, and DAVID COLE, a citizen of the United States, and resident of El Paso, county. of El Paso, Texas, have invented an Improvement in Processes and Apparatus for Separation of Ores by Flotation, of which the following description, in connection with the accompanying drawing, is a specification, like characters on the drawing representing like parts.

This invention relates to improvements in process and apparatus for recovering valuable minerals by flotation, and particularly of the type in which the selective action of oils is utilized to cause the separation of the valuable minerals from the gangue and their recovery by flotation in froth generated by the agitation of the finely divided ore and water in the presence of oil .or oleaginous material alone or oleaginous material and certain acids or other chemicals useful in increasing the selective affinity of the oil for value bearing minerals.

The process aforesaid is largely used commercially in the separation of metallic sulfid such as the sulfids of zinc, copper, lead and silver from quartz and other non-valuable gangue.

In the utilization of this process the ore in a very finely divided state is mixed with a small quantity of oil and is violently agitated in water. The selective affinity of the oil for the sulfid particles causes the latter to adhere to or be inclosed in a film of the oil and the violent agitation induces air bubbles to the mantles of which the fine particles of valuable sulfids adhere. These gas or air bubbles rising to the surface produce a froth which is skimmed off mechanically then broken down and the resulting slime concentrate reduced and refined in the usual manner.

The breaking down of the froth has heretofore been accomplished by playing a stream or streams of water upon the same, thus adding a large amount of water to the slime, which has to be removed before the slime is in condition for reduction.

The present invention consists in intro- Specification of Letters Patent.

State of Patented Apr. is, rare.

Serial No. 71,968.

ducing a novel step in the flotation process which results in the complete breaking down of the froth and at the same time keeping the volume of water used within the smallest washing away of the valuable concentrates by an unnecessarily large volume of water. This is accomplished by subjecting the froth to the action of other gaseous fluid under pressure in combination with a very fine such as water. The jets are produced by the compressed air, steam, or other fluid, just a sufiicientamount of water being supplied to effect the breaking down of the froth and to cause the slime to flow into a settling tank or other receptacle.

The step in the process herein described may be utilized successfully in connection with any of the well known types of apparatus used commercially in performing the flotation process.

As an illustrative embodiment of the invention the accompanying drawings show means for introducingthis novel step in the flotation process into the Callow type of flotation apparatus. In this illustration only a single roughing cell of the Gallow apparatus is disclosed with a suitable nozzle associated therewith to perform the novel step herein described, but it will be understood that in practice a battery of such cells may be used together with such secondary, or cleaner cells as may be desirable to effect a complete separation of the values of the ore from the gangue.

In the drawing, Figure 1 is a vertical sectional view of a preferred form of mixer and Callow cell showing a spray nozzle especially adapted for the breaking down of the froth, Fig. 2 is a plan view of the same, Fig. 3 is a view partly in section of a preferred form of nozzle adapted to be used for the )rocess set forth, Fig. i is a detail sectiona view showing an adjustable diaphragm for regulating a current-of air forming an envelop surrounding the atomizing jet discharged from the nozzle, Fig. 5 is a vertical sectional view through the nozzle on lines 55, Fig. 3.

The apparatus disclosed in the drawings comprises a preferably cylindrical mixing practical limits thus preventing the spray of liquid a jet or jets of air or tion 2 and an inlet pipe 3 having at its upper end, a hopper leading into the said mixing chamber adjacent the upper portion of the conoidal base of the receptacle, an outlet pipe .4: located within the top of the receptacle andleading to the Callow separating cell. The ore is introduced through a pipe 5, the oil having previously been added to the ore; or the oil may be supplied throughthe pipe 6 also leading into the inlet pipe 3.

In order to cause an agitation of the material introduced, into the mixture 'the nozzle 7 of a compressed air pipe is fixedly secured centrally in the conoidal bottom of the receptacle, the end of said nozzle extending a short distance into a vertical pipe 8, which is provided-near its bottom with apertures 9 and which extends nearly tothe level of the outlet pipe 4. A baffle plate 10, which may be in the form of an inverted cone supported above the top ofthe tube 8- by brackets 11 serves to deflect the material discharged from the pipe 8 back into the mixer.

In the operation of the device the compressed air passing through the nozzle 7 causes inspiration of the mixed ore, water and oil through the holes 9 in the pipe, driving the samethrough the tube 8 and causing a rapid circulationin the chamber of the mixing receptacle. The air thusintroduced also incorporates in the mixture :1 large number of fine bubbles. Ore and water may be continuously supplied to this receptacle so that the overflow therefrom will fill the Callow cell to the desired height and maintain it at such height during the operation of the process.

The Callow cell as illustrated herein comprises a rectangular box, preferably constructed of wood, having vertical sides 12, 13, ends 14, 15 and an inclined bottom 16. At the inlet end of the cell a partition 17 is provided, having near its bottom an aperture 18 which communicates with the interior of the cell below the surface of the mixture therein, preferably at or near the bottom of the cell. v V v Troughs 19 and 20 extend longitudinally of the cells, the bottoms 21 of said troughs backing of perforated metal 26 to prevent.

its bulging. A sinuous metallic bottom plate 27 is desirably provided beneath the porous medium divid ng the space into several compartments, eight as shown herein, to each of which is connected an individual pipe 28 leading from a compressed air pipe 29, valves 30 being provided in said pipes 28 so that the air pressure to each compartment may be regulated so as to discharge a uniform amount of air throughout the length of the bottom, and thus maintain a uniform aeration of ,the contents. Apressure of from four to five pounds in the conduit pipe 29 is usually sufficient to properly operate a cell approximately nine feet long, two feet wide and twenty inches deep at its shallow. end and forty five at its deep end. The cell is preferably provided at its lowest portion withan Outlet 31 for the discharge of the gangue. This outlet desirably is regulated by means of a float valve -32 the stem of which may conveniently be attached to a lever 33 which is pivotally secured at one end to a plate 3% at the end of the tank and provided at its oppositeend with a depending arm 35. having a float 36 attached thereto.

In the commercial practice ofthe flotation process the rougher cell, such as the one illustrated herein, is'followed by any desired number of similar cleaner cells for the purpose of further concentrating the ore and effecting, as nearly as possible a complete separation. The tailings or middlings discharged at the outlets of the cleaner cells whichv are rich in mineral but too siliceous to be readily smelted are returned to the" mixer by a centrifugal pump, or other suitable device (not shown) through the pipe 37 while the froth bearing the clean conce'ntrates is broken down and the concentrates delivered to a suitable'tank or other receptacle. V V

In the operation of the cell the water level is maintained at from six to twelve inches below the level of the upper edges of the lips of'the-walls12, 13 of the trough and the froth flows over these edges or lips into the troughs 19, .20. The.bottoms' 21' of the troughs 19, 20 are sufficiently inclined to cause the froth to .flow with suflicient rapidity to prevent piling up or accumulation thereof. Heretofore the froth has been delivered from these troughs into a main trough and a stream or jets of water played upon it to break the same down and reduce the oil and concentrates carried thereby into the form of slime. As above stated this results in the addition of an undesirable amount of water to the concentrates which must be removed beforethe concentrates can be reduced. It also results in washing away more or less of the valuable concentrates. In order to overcome this objection and to more effectively break down the froth, the presentinvention contemplates the providing of means for treating the froth with a fluid under pressure, such as compressed air,

steam or like gaseous fluid or vapor which 41 to the same compressed air main as the compressed air pipe 29 which delivers the compressed air to the bottom of the Callow cell. The compressed air pipe 41 desirably is provided with a valve 42 which, if high pressures are used in the main, may be in the form of a reducing valve. Inasmuch ihOVVGVQI' as the pressure required to supply the Callow cell and that required to supply the atomizer is substantially the same such reducing valve will not ordinarily be required A preferred type of nozzle which may be successfully used in the performance of this step in the flotation process-is illustrated in the prior patent to Albert W. Thompson No. 965,963 granted Aug. 2, 1910. A modified form of said nozzle is illustrated herein which may be easily regulated to produce the most efiicient spray for breaking down the froth produced in the flotation process. This nozzle comprises an elongated tubular casing 43 which preferably is somewhat reduced in diameter at'its open end 44 and is closed at its opposite end 45v and provided with a suitable gland or stuffing box 46 for the stem of a fluid controlling valve 47 of any suitable construction which is illustrated herein as a needle valve adapted to cotiperate with a valve seat placed in the wall 49. of an inlet conduit or chamber 50 which communicates withthe fluid supply pipe 51. A centrally disposed'tube or conduit 52 preferably formed integral with the casing and having a central duct 52 serves, to supplythe water to the'nozzle under the regulation of the valve 47.

The end of the conduit 52 is preferably provided with an enlarged portion or spider 53 having integral radial arms 54 connecting the same with the wall 'of the casing. The central portion of the outer end of the conduit 52 is provided with an enlarged screw threaded opening in which liquid supply nozzles 55 having diflerent apertures may be detachably secured.

The nozzle 55 is screw threaded eXteriorly to fit the enlarged aperture in the end of the conduit 52 and is conveniently retained therein by a set nut 56 abutting against the end of the spider 53. The outer face of the spider 53 preferably is provided with a concentric annular recess 57 which provides a seat for the inner end of a nozzle 59 having an atomizing chamber into which the fluid under pressure is introduced tangentially.

The wall of the end portion of the atomizing nozzle 59 preferably is reduced to provide an annular shoulder 60 in the same plane as the end of the casing 43.

A retaining ring 61 secured upon the end of the casing 43 engaging the shoulder 60- holds the atomizing nozzle 59 securely in position. This retaining ring may be in the form of a blank serving to close the outlet of the casing surrounding the tubular member 59. It is however desirable to provide means for varying the form of field and the character of the jet. This may conveniently be accomplished by providing the retaining ring with an annular series of apertures 62 and interposing a diaphragm 63 having complementary apertures 64 between said ring 62 and the shoulder 60. The diaphragm 63 may be rotarily adjusted by means of a handle extending through a recess in the wall of the casing 43. In this latter construction the ring 62 preferably is provided with an internally screw threaded extension upon which is screwed a conical inclosing nozzle 65 of somewhat larger diameter than the diameter of the atomizing nozzle 59 so that when the apertures in the ring 62 and diaphragm 63 register, more or less, an annular jet is formed which incloses the jet delivered from the atomizing nozzle 59.

The area of the annular orifice surrounding the atomizing nozzle may be varied within the required limits of-adjustment by screwing the inclosing nozzle into the ring 62 to a greater or less depth, thereby regulating the annular enveloping airjet.

The nozzle 59 is provided with one or duced from the supply pipe 41. By reason of this tangential arrangement of the inlets, the fluid under pressure, when admitted to the atomizing chamber within the nozzle, assumes a rotary or whirling motion of relatively high velocity, breaking up or pulverizing the liquid admitted through the inner nozzle 55 so that there issues from the atomizing nozzle a whirling jet of gaseous fluid in which are suspended or commingled minute globules of the liquid. The size of the liquid globules may be varied by controlling the pressure of the gaseous fluid supply since a high pressure will cause a finer division of the liquid introduced through the central or axialnozzle.

If the diaphragm is so adjusted as to prevent the passage of air through the ports in the diaphragms 62 and 63 the jet discharged from the nozzle 59 will be in the form of a cone having a wide angle which frequently may be very effectively used. In most instances however it is desirable to confine the jet more narrowly and .to accomplish this purpose the diaphragm 61 may be adjusted to permit the gaseous fluid under pressure to escape through the apertures in the diaphragm into the conical nozzle 65 which surrounds the end of the nozzle 50 and ex tends a short distance therebeyond. The gaseous fluid from the interior of the casing passing through this nozzle forms an annular jet completely surrounding the jet carrying the atomizing liquid which is discharged from the nozzle 59. This envelop of gaseous fluid serves the double purpose of concentrating the fluid carrying jet into substantially cylindrical instead of conical form and also supplying an additional amount of gaseous fluid which aids in breaking down the froth.

In the operation of the device the nozzle l0 desirably is placed above the end of the trough which delivers the froth, the axis of said nozzle being presented at an angle preferably of from sixty to ninety degrees to the plane of the bottom of the trough so that the jet of gaseous fluid with its commingled globules of liquid will impinge upon the froth at a suflicient angle to delay the flow slightly so that each and every bubble of the froth will be broken down and the slime will pass over the end of the trough as a liquid mass and ready to be reduced.

In practice the nozzle should be placed at such a distance from the trough that the field of the jet will entirely cover the cross sectional area of the trough, the amount of water delivered to the nozzle being regu-' lated by adjustment of the valve 47 in such a manner as to give the most eflicient results.

It is to be understood that the particular apparatus disclosed herein is illustrative of the preferred form of apparatus now known to us but that other types of jet producing apparatus in which the effective jet comprises a gaseous fluid under pressure with globules of liquid commingled therein are r within the scope of our invention as defined in the following claims.

It will be readily understood that various kinds of gaseous fluid may be utilized such as compressed air, steam, or various gases which may or may not have a chemical action upon the minerals of the froth bubbles and that the liquid supplied may be water or any other liquid including acids or acidulated fluids adapted to increase or aid in the breaking down of the froth or in the reduction of the slime.

Having thus described our invention, what we claim as new and desire to secure by Letters Patent is;

1. An improvement in the step of breaking down the froth in the flotation process of recovering metallic contents from ores, which consists in impinging the froth with a jet of gaseous fluid commingled with globules of a liquid.

2. An improvement in the step of breaking down the froth in the flotation process of recovering metallic con-tents from ores which consists in impinging the froth with a whirling jet of gaseous fluid commingled with globules of a liquid.

3. An improvement in the step of breaking down the froth in the flotation process of recovering metallic contents of ores which consists in producing a whirling jet of gaseous fluid, introducing a liquid axially into said jet thereby causing the liquid to be suspended in the jet in the form of lobules andthen impinging the jet thus formed uponthe froth.

ing down the flowing of froth formed in the flotation process of recovering metallic contents from ores which consists in impinging the froth with a jet of gaseous fluid commingled with globules of liquid at an angle .to the direction of flow of the froth Whereby the froth will be retarded until all or substantially all of the bubbles formed in the same are broken down.

5. In an apparatus of the class described comprising means for producing a froth bearing metallic concentrates, means for subjecting said froth to a jet or blast of fluid under pressure containing finely divided particles of a non-gaseous material.

6. In an apparatus of the class described comprising means for producing a' froth bearing metallic concentrates, means for subjecting said froth to a jet or blast of fluid under pressure containing finely divided particles of a non-gaseous material.

7. In an apparatus of the class described comprising means for producing a froth bearing metallic concentrates, means for impinging said froth with a whirling jet of gaseous fluid commingled with globules of a liquid.

8. In an apparatus of the class 'described comprising means for producing a froth bearing metallic concentrates, means for impinging said froth with a whirling jet of gaseous fluid commingled with globules of a liquid, and means for discharging a non-rotatable jet of air around the said whirling jet.

9. In an apparatus of the class described comprising means for producing a froth bearing metallic concentrates, means for producing a whirling jet of gaseous fluid, means for introducing liquid axially into said jet thereby atomizing said lquid and causing the same to be suspended in said jet in the form of globules and impinging the jet thus formed upon the froth.

10. In an apparatus of the class described comprising means for producing a froth bearing metallic concentrates, means for collecting said froth and causing the same to flow slowly, means for directing a jet 0 I. An improvement in the step of breakof gaseous fluid having commingled therein globules of a liquid at an angle to the direction of flow of said froth whereby the flow of the froth is retarded. and the mantles of the froth bubbles broken down.

11. In an apparatus of the class described comprising means for producing a froth bearing metallic concentrates, means for breaking down said froth comprising a nozzle having an atomizing chamber provided rounding the atomizer outlet, and means for with an axial outlet, means for introducing a fluid under pressure tangentially into said chamber, means for supplying a liquid axiqjally of said chamber and means for direct ing the jet from the nozzle upon said froth.

12. In an apparatus for recovering metallic values from ores by flotation, means for causing flotation of the metallic concentrates in a froth, means for breaking down the froth comprising a nozzle consisting of a casing having a tubular outlet connecting with a supply of fluid under pressure, a central atomizing chamber, means for supplying a liquid axially to said chamber and means for supplying a fluid under pressure tangentially to said chamber whereby a whirling spray is produced surrounded by an annular envelop of non-rotatable fluid and means for directing the jet thus formed upon said froth.

13. In an apparatus for recovering metallic values from ores by flotation, means for causing. flotation of the metallic concentrates in a froth, means for breaking down the froth comprising a nozzle consisting of a casing having a tubular outlet connecting with a supply of fluid under pressure, a central atomizing chamber, means for supplying a liquid axially to said chamber and means for supplying a fluid under pressure tangentially to said chamber whereby a whirling spray is produced surrounded by an annular envelop of non-rotatable fluid and means for regulating the annular blast of air projected through the nozzle surdirecting the jet thus formed upon said froth.

14. In an apparatus for recovering metallic values from ores by flotation, means for causing flotation of the metallic concentrates in a froth, means for breaking down the froth comprising a nozzle consisting of a casing having a tubular outlet connecting with a supply of fluid under pressure, a central atomizing chamber, means for supplying a liquid axially to said chamber and means for supplying a fluid under pressure tangentially to said chamber whereby a whirling spray is produced surrounded b an annular envelop of non-rotatable fluid an adjustable diaphragm for regulating the annular blast of air projected through the v nozzle surrounding the atomizer outlet, and means for directing the jet thus formed upon said froth.

In testimony whereof, wehave signed our names to this specification.

ALBERT W THOMPSON. DAVID COLE. 

